Pallet elevator



July 31, 1962 c. L. BELL ETAL PALLET ELEVATOR 3 Sheets-Sheet 1 Filed May6, 1960 INVENTORS QM MNM Q P 4 r i 4 AH as w MW July 31, 1962 c. 1..BELL ETAL 3,047,095

PALLET ELEVATOR Filed May 6, 1960 5 Sheets-Sheet 2 IN V EN TORS 048/. A5 55L 4 M44 04M SfZE/V/IK QFPP July 31, 1962 c. BELL ETAL 3,047,095

PALLET ELEVATOR Filed May 6, 1960 3 Sheets-Sheet 3 INVENTORS we; 45 55LL a; 4 MM 35/. 5mm PfPP AGE/VT United States Patent 3,047,095 PALLETELEVATOR Carl Lee Bell, Kenoslia, Wis., and William Selenak Repp,

Waukega'n, Ill., assignors to American Can Company, New York, N. Y., acorporation of New Jersey Filed May 6, 1960, Ser. No. 27,415 Claims.(Cl. 1873) The present invention relates to palletizing anddepalletizing machines and has particular reference to a hydraulicallyoperated chain lift pallet elevator.

The use of palletized can loads in the can making and canning industriesfor'the handling and storing of cans has greatly increased in recentyears because such loads make possible the greater use of fully orsemi-automatic can-handling equipment with resultant economic benefits.

However, these benefits can only be obtained where the capitalexpenditures necessary for the purchase of such equipment are not beyondthe economic capabilities of the individual company or plant desiring toadopt this method of handling cans. This is particularly true of smallcanning companies having limited financial assets.

Consequently, there is a great need for simple and inexpensive equipmentwhich can be used to handle palletized loads of cans. The presentinvention provides a hydraulically driven pallet elevator constructionwhich is suitable for incorporation in such equipment.

Accordingly, an object of the instant invention is the provision of asimple, inexpensive, and reliable pallet elevator wherein a singlehydraulic cylinder is utilized to drive paired elevator lift chains inopposite directions so that their inner, opposing, elevator supportingflights all move in the same direction.

Another object of the invention is the provision of such an elevatorwhere a single hydraulic cylinder is utilized to drive the elevator liftchains through a lift stroke which is much longer than the stroke of thehydraulic cylinder.

Numerous other objects and advantages of the invention will be apparentas it is better understood from the following description, which, takenin connection with the accompanying drawings, discloses a preferredembodiment thereof.

Referring to the drawings:

FIGURE 1 is a plan view of a can depalletizing machine incorporating apallet elevator which embodies the principles of the instant invention;

FIG. 2 is a side elevation of the machine of FIG. 1;

FIG. 3 is a vertical section on an enlarged scale taken substantiallyalong the line 33 in FIG. 2;

FIG. 4 is a vertical section, on an enlarged scale, taken substantiallyalong the line *44 in FIG. 3; and

FIG. 5 is a schematic view illustrating the various components of theelevator drive mechanism of the instant invention.

As a preferred and exemplary embodiment of the instant invention, thedrawings disclose a depalletizing ma chine wherein palletized loads L ofindividual articles such as cans C are received on the inlet end of aconveyor which comprises a pair of spaced and parallel endless feedchains 11, 12 which at their opposite ends operate around pairs of drivesprockets 13, 14 mounted respectively on cross-shafts 15, 16. Thecross-shaft 16 is preferably driven by asuitable motor drive (notshown). The horizontal, upper flights 18 of the chains '11, 12 ride insupport channels (not shown) which prevent them from sagging beneath theweight of the load L.

Each palletized load L comprises a conventional support pallet P whichis usually made of wood and which carries on it a plurality ofhorizontal layers of individual, upright cans C, each layer carrying onits upper surface ice a chipboard separator sheet S which forms a stablebase for the superposed layer.

The depalletizing'machine includes a frame 20 through which the feedchains 11, 12 operate. The frame 20 is preferably built up of suitableangle irons and channel bars, and forms a support for a pair of sidewalls 22 and a rear end wall 24, these three walls in effect creating anunloading compartment 26 which receives a palletized load L as it is fedhorizontally by the feed chains 11, 12. The front end of the compartment26 is open to permit entry of the load L.

When the load L is fully within the unloading compartment 26, theconveyor 10 is stopped, preferably by a suitably located stop switchwhich is tripped by the pallet P when it reaches the desired position.Since this stop switch forms no part of the instant invention, it is notshown in the drawings. After the conveyor 10 stops, the load L is movedupwardly off the chains 11, 12 by an elevator, generally designated bythe numeral 28 (see FIG. 5), which comprises a pallet support which inthe instant embodiment is formed of a pair of transverse support bars 30which engage the bottom surface of the pallet P. The support bars 30are, while the load L is being fed into the unloading compartment 26,positionedbcneath the level of the pallet P in depressions 32 which areformed in the upper flights =18 of the chains 11, 12. There are two suchdepressions 32 formed in each chain 11, 12, the depressions 32 in chain11 being disposed in transverse alignment with those in chain 12. Eachdepression 32 is created by having the upper chain flights 18 operatearound and over a pair of longitudinally spaced small sprockets 34, 36and beneath a third small sprocket 38 which is mounted intermediate andat a lower level than the sprockets 34, 36 see FIG. 2).

Each support bar 30 is secured at its opposite ends to a pair of opposedvertically mounted endless lift chains 40, 42 which are mounted inopposition to each other onopposite sides of the frame 20 and operate invertical planes which are disposed at right angles to the conveyor 10. Asecond pair of side walls 43, 44 are preferably disposed outwardly ofthe chains 40, 42 to provide a protective covering. V

At their upper ends, the chains 40, 42 operate around small sprockets 45which are mounted on a pair of longitudinal shafts 46 which arejournalled in bearings (not shown) secured to the machine frame 20. Attheir lower ends, the chains 40, 42 operate around large sprockets 50which are keyed to a pair of longitudinal shafts 52 53 which arejournalled in bearings (not shown) which are also secured to the frame20. Since the lower sprockets 50 are larger than the upper sprockets 45,the lower shafts 52, 53 are offset outwardly with respect to the uppershafts 46 so that the inner flights of all of the lift chains 40, 42 arevertically disposed to maintain a uniform, spacing therebetween. Theinner side walls 22 are suitably slotted inwardly of the chains 40, 42to permit the support bars 30 to be raised by the chains 40, 42 forsubstantially the full height of the unloading compartment 26.

The elevator 28 is actuated by a drive mechanism which includes a singlehydraulic cylinder 60 ,which extends transversely across the conveyor 10and is supported by a channel plate 62 which is secured in the machineframe 20, the rear end of the hydraulic cylinder 60 being secured to ablock 64 which is fastened to the underside of the channel plate 62 andthe front end of the cylinder being secured to a block 66 which is alsofastened to the channel 62.

The hydraulic cylinder 60 contains a conventional reciprocating piston68 to which is secured a piston rod 70 which projects from the cylinderand carries a short cross bar 72. One end of the crossbar-72 has securedto it ond endless drive chain 84 (see FIGS. 3, 4 and S).

The endless chains 78, 84 are mounted in parallelism in vertical planeswhich extend transversely of the conveyor 10 on either side of thehydraulic cylinder 60.

The chain 78 operates around an idler sprocket 86 which is freelymounted on a short longitudinal drive shaft 88 which is journalled in apair of bearings 90 which are mounted on the underside of the channelplate 62 (see FIGS. 3 and 4). The chain 78 also operates around asprocket 92 which is keyed to and drives a second short longitudinaldrive shaft 94 which is mounted in a pair of bearings 96 which are alsosecured to the underside of the channel plate 62 on the opposite side ofthe machine (see FIG. 3.)

The chain 84 operates around a sprocket 98 which is keyed to and drivesthe drive shaft 88, and around an idler sprocket 100 which is freelycarried on the shaft 94.

The adjacent ends of the shafts 52 and 88 are operatively connected by ashort endless chain 102 which operates around a pair of sprockets 104,106 which are keyed to the ends of the shafts 88 and 52 respectively, sothat both of these shafts rotate in the same direction. In a similarmanner, the adjacent ends of the shafts 3 and 94 are operativelyconnected by a short endless chain 108 which operates around a pair ofsprockets 110, 112 which are keyed respectively to the shafts 94 and 53,so that these shafts also turn in the same direction.

The hydraulic cylinder 60 is connected into a closed hydraulic systemwhich includes a circulating pump P which is driven uni-directionally byan electric motor M so that the fluid in the system flows from the pumpP through a supply pipe 114 and enters it through a return pipe 116. Asuitable control valve 118 is interposed, bebtween the pipes 114, 116and is provided with a movable internal valve slide 120 which isprovided with suitable ports (not shown) which bring the supply pipe 114selectively into communication with one or the other of a pair of pipes122, 124 which are connected into the opposite ends of the hydrauliccylinder 60. The valve slide 120 also is provided with ports (not shown)which bring the return pipe 116 into communication with that pipe 122,124 which at such time is out of communication with the supply pipe 114.The valve slide 120 also has a neutral position wherein both outletpipes 122, 124 are shut ofl? from both the supply pipe 114 and thereturn pipe 116.

The valve slide 120 is connected to a pivotally mounted handle 126 sothat it can be manually moved to any of its control positions at thewill of the operator. The actual interior construction of the controlvalve 118 and the valve slide 120 are not disclosed, since they arecompletely conventional. The usual by-pass line 128 and bypass valve Vare provided to maintain a uniform pressure within the system.

From the foregoing, it will be seen that when the fluid is introducedinto the pipe 124, a pressure is exerted against one side of the piston68, with the result that it is moved to the fully retracted positionwhich is disclosed in FIGS. 3 and 5. In such position, the cross-bar 72is positioned substantially midway of the conveyor and the support bars30 are disposed at the bottom of their stroke and are positioned withinthe recesses 32.

As soon as the palletized load L is fed into position within theunloading compartment 26, the conveyor 10 is stopped. The handle 126 isthen manipulated by the operator of the machine to move the valve slide120 to a position where it brings the pipe 122 into communication withthe supply pipe 114, and at the same time connects the pipe 124 with thereturn pipe 116. As a result, the piston 68 is moved within the cylinder60 away from its fully retracted position, and the chains 78, 84 aremoved in opposite directions because of the fact that the crossbar 72 issecured to the upper flight 76 of the chain 78 and to the lower flight82 of the chain 84.

Since the chain 78 drives the drive shaft 94 and the oppositely movingchain 84 drives the other drive shaft 88, these shafts also rotate inopposite directions and in turn rotate the shafts 52 and 53 in oppositedirections. As a result, the elevator lift chains 40, which are drivenby the shaft 53, are driven in a direction opposite to the direction inwhich the lift chains 42, which are driven by the shaft 52, are driven.Consequently, the inner flights of all of the lift chains 40, 42 aremoved in the same direction, i.e. upwardly, thus moving the support bars30 upwardly. The directions of movement of all of the various elementsof the instant mechanism which effect this upward movement of thesupport bars 30 are indicated by arrows in FIG. 5.

As best seen in FIGS. 3 and 5 the sprockets 50 are considerably largerin diameter than the sprockets 86, 92, 98, 100, 104, 106, or 112, theselatter preferably being of a uniform diameter. Since the shafts 52, 53rotate at a one to one ratio with the drive shafts 88, 94, the result isthat the lift chains 40, 42 are moved by the cylinder 60 through adistance which is greater than the distance of movement of the piston68, the ratio of these distances being the same as the ratio of thediameter of the sprockets 50 to the diameter of the smaller sprockets106, 112. This is very advantageous in that it makes possible the use inthe machine of a hydraulic cylinder having a short operating stroke.

The upward movement of the lift chains 40, 42 initially brings thesupport bars 30 into contact with the pallet P and thereafter continuesuntil the palletized load L is raised to a level wherein the uppermosthorizontal layer of cans C in it is brought into horizontal alignmentwith a wide endless take-away belt 136, at which time the handle 126 ismoved to its neutral position to stop the ascent of the elevator.

One end of the belt 136 operates around a drum 138 which is journalledin the machine frame 20. At its other end, the take-away belt 136operates around a second drum (not shown), which is suitably driven sothat the upper flight of the belt 136 moves in a direction away from theunloading compartment 26. To unload the cans from the palletized load L,the machine operator need merely use a wide pusher bar to manually pushthe cans across a support plate 140 and onto the belt 136 for deliveryto the desired place of deposit. Suitable side guides (not shown) areprovided to maintain the cans against undesired lateral movement duringthis transfer. If desired, the uppermost layerd of cans may be sweptonto the belt 136 by a mechanical pusher arm (not shown).

After the uppermost layer of cans C has thus been removed from the loadL, the handle 126 is again manipulated to reconnect the pipe 122 withthe supply pipe 114 to move the piston 68 further to the right, asviewed in FIGS. 3 and 5, to thereby cause the support bars 30 to againmove upwardly to bring the next layer of cans C in the palletized load Lto the level of the take-away belt 136. The chipboard separator sheet Shaving been removed, the cans C in the next layer are pushed onto thetake-away belt 136 and delivered to the place of deposit. This unloadingoperation is continued until such time as all of the layers are removedfrom the pallet P.

When this occurs, the handle 126 is moved into position to connect thepipe 124 with the supply pipe 114, and to simultaneously connect thepipe 122 with the return pipe 116, thereby causing the piston 63 toreverse itself and move in the opposite direction (to the left as seenin FIGS. 3 and 5) and to assume the retracted position of FIG. 3, thuscausing the support bars 30 to move downwardly and enter the recesses32. During the latter 7 portion of this downward movement of the supportbars 30, the new empty pallet P is deposited on the chains 11, 12.

The conveyor is once again started up, in the same direction as before,to remove the empty pallet P from the unloading compartment 26. Thismovement is not obstructed by the end wall 24 of the loading compartment26, since the bottom edge 142 of this wall 24 is disposed above theupper surface of empty pallet P, as seen in FIG. 3. Assuming that a newpalletized load L has been previously positioned on the inlet end of theconveyor 10, this same movement of the conveyor 10 moves the new load Linto unloading position within the unloading compartment 26 of themachine. When the new load L has thus been positioned, the conveyor 10is stopped and the can unloading operation just described is againrepeated.

It is clear that the machine which has been described is equally welladapted for use as a can palletizing machine. In such a machine, thebelt 136 would be reversed and used as a can infeed belt, and the palletP would initially be raised to its uppermost position and graduallylowered as the layers of cans are built up on it.

It is thought that the invention and many of its attendant advantageswill be understood from the foregoing description, and it will beapparent that various changes may be made in the form, construction andarrangement of the parts without departing from the spirit and scope ofthe invention or sacrificing all of its material advantages, the formhereinbefore described being merely a preferred embodiment thereof.

We claim:

1. A hydraulically operated elevator for raising and lowering a palletand the like, comprising a support engageable beneath said pallet, apair of parallel shafts disposed on opposite sides of said support, apair of endless lift chains operating around and driven by each of saidshafts,- the opposed inner flights of said lift chains extendingvertically and secured to said pallet support, a pair of endless drivechains disposed in spaced parallel relation in vertical planes extendingtransversely of said shafts, said chains each including spaced parallelflights, means operatively connecting said drive chains to said shaftsrespectively, and means extending between said drive chains and securedat opposite ends to different spaced flights thereof for simultaneouslydriving the chains in opposite directions, whereby to rotate said shaftsin opposite directions while moving said inner lift chain flights in thesame vertical direction.

2. The mechanism of claim 1 wherein said drive chains are formed withupper and lower horizontally extending flights, and wherein the meansfor driving said drive chains in opposite directions comprises a fluidactuated cylinder having a reciprocable piston connected to the upperflight of one of said drive chains and to the lower flight of the otherdrive chain.

3. A hydraulically operated elevator for raising and lowering a palletor the like, comprising in combination a pallet support engageablebeneath said pallet, a pair of mounted in parallelism on opposite sidesof said support, a pair of sprockets keyed to each of said shafts,

' a pair of endless lift chains operating around and driven by saidsprockets respectively, the inner flights of said lift chains extendingvertically and being secured to said pallet support, a pair of rotatabledrive' shafts mounted in parallelism with said first named shafts, meansfor transmitting the rotation of said drive shafts to said first namedshafts, a pair of sprockets carried on each of said drive shafts, thesprockets on one of said drive shafts being transversely aligned withthose on the other drive shaft, a pair of spaced parallel endless drivechains each including spaced parallel upper and lower flights mountedfor operation around said aligned sprockets respectively, a fluidactuated cylinder mounted in parallelism with said drive chains, areciprocable piston disposed within said cylinder, and means securingone end of said piston to different flights of said drive chainsrespectively whereby rectilinear movement of said piston in onedirection is utilized to actuate said lift chains in unison to move saidpallet support in a vertical direction.

4. The mechanism of claim 3 wherein the sprockets on said first namedshafts are of larger diameter than the sprockets on said drive shafts tothereby increase the vertical distance traversed by said lift chainsrelative to the length of the piston movement.

5. A hydraulically operated elevator for raising and lowering a palletor the like, comprising in combination a pallet support engageablebeneath said pallet, a pair of shafts mounted in parallelism on oppositesides of said pallet support, a pair of sprockets keyed to each of saidshafts, an endless lift chain operating around and driven by each ofsaid sprockets, said lift chains being disposed in vertical planes whichextend transversely of said shafts, the inner flights of each of saidlift chains extending vertically and being secured to said palletsupport, a rotatable drive shaft disposed in parallelism to each of saidfirst named shafts, means for transmitting the rotation of each of saiddrive shafts to its. associated first named shaft so that the latterrotate in the same direction as the former, a pair of sprockets disposedin spaced relation along each of said drive shafts, the sprockets on oneof said drive shafts being transversely aligned with the sprockets onthe other of said drive shafts to form two pairs of transversely alignedsprockets, one of the sprockets of one of said transversely alignedpairs thereof being keyed to one of said drive shafts and one of thesprockets of the other of said transversely aligned pairs thereof beingkeyed to the other of said drive shafts, the remaining two sprocketsbeing idler sprockets, a pair of spaced and parallel endless drivechains operating around said transversely aligned pairs of sprockets andextending in a substantially horizontal direction between said driveshafts, a fluid operated cylinder disposed between said drive chains, areciprocable piston disposed in said cylinder, and means connecting saidpiston to the upper flight of one of said drive chains and to the lowerflight of the other of said drive chains whereby said piston moves saiddrive chains in opposite directions and the motion of said drive chainsis transmitted to said lift chains to move their inner flights in thesame direction.

References Cited in the file of this patent UNITED STATES PATENTS2,405,691 Ellis Aug. 13, 1946 2,553,962 =Duford May 22, 1951 2,936,639Philippi May 17, 1960

